Hook: Floor Medium (Blue Square)The Skytrooper Praetorian Armor Display decoration fits into a blue medium square floor hook.
How to Get a Skytrooper Praetorian Armor Display Decoration
Star Fortress Decorations
Star Fortresses are a type of solo or group content similar to flashpoints. You can not access Star Fortresses until you have completed Chapter 9 of Knights of the Fallen Empire (level 60+). The enemies in the Star Fortress have a chance of dropping bunch of different Star Fortress and Skytrooper Decorations, including the Skytrooper Praetorian Armor Display decoration.
You can usually also find most Star Fortress decorations on the GTN, sold by other players who won them while doing a Star Fortress.